Glider
Captain
I am afraid that I cannot remember the accuracy but I did read of a Beaufighter unit who set the 20mm harmonisation at 800 yards and when the shells started hitting the ship in line with the sights then they would salvo the rockets
Dive bomber accuracy in perspective.
- Thread starter davebender
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yulzari
Staff Sergeant
Being set together in the base of the fuselage I was under the impression that Beaufighter Hispanos were aligned not harmonised. i.e. set to fire straight ahead not to converge. Possibly the reference is to the sights such that the fire and sight setting matched at 800 yards so when the sight and fire were together the range was 800 yards and the RPs fit to fire. Above 800 yards the Hispano fire would be below the sight and closer above. Or maybe the .303s in the wings were harmonised to meet at 800 yards like the 2x.303s in a Hurricane IID?
Glider
Captain
The first part of your post is what I was trying to say. Rocket armed Beaufighters didn't carry the LMG.
By far most of the calories burned figuring out a proper harmonisation is done in the vertical sense, not merely where the bullet streams cross (if at all).
I by no means have exhaustive data on the subject, but standard 1945 Coastal Command RP harmonisation vs. surface targets was for:
" ... a firing range of 600 yards in a 12.5 degree dive with an airspeed of 285 knots. The top of the freeboard of the ship should be taken as a point of aim for the cannon at the start of the run-in, and if the rockets are fired at 600 yards the centre of the salvo should hit 50 ft. short."
I've seen 1944 harmonisations that call for level-flight attacks at 250 mph IAS.
I by no means have exhaustive data on the subject, but standard 1945 Coastal Command RP harmonisation vs. surface targets was for:
" ... a firing range of 600 yards in a 12.5 degree dive with an airspeed of 285 knots. The top of the freeboard of the ship should be taken as a point of aim for the cannon at the start of the run-in, and if the rockets are fired at 600 yards the centre of the salvo should hit 50 ft. short."
I've seen 1944 harmonisations that call for level-flight attacks at 250 mph IAS.
Ascent
Senior Airman
This has inspired me to reread 'A separate little war' about the Banff strike wing.
It mentions two boats and talking about armament it says "Both carried two 105mm guns, one 37mm anti-aircraft gun, one quadruple mounted 20mm anti-aircraft gun, four twin mounted 20mm anti-aircraft guns and four rocket dischargers."
Even with a relatively low rate of fire that's a lot of lead being thrown in the air.
It mentions two boats and talking about armament it says "Both carried two 105mm guns, one 37mm anti-aircraft gun, one quadruple mounted 20mm anti-aircraft gun, four twin mounted 20mm anti-aircraft guns and four rocket dischargers."
Even with a relatively low rate of fire that's a lot of lead being thrown in the air.
Ascent
Senior Airman
Another quote from 'A separate little war', describing how they attacked. This is attributed to Squadron leader Bill Clayton-Graham.
"Normally when making an attack on shipping, the dive at 45 degrees was started at 2,000 feet, opening up with machine guns as sighters at about 1,500 to 1,000 feet. Hopefully the cannons were to knock out the enemies guns, bridge and so forth, and we then fired the rocket projectiles at about 500 feet. These were set to form a pattern spread on impact, so that if aimed correctly about half hit the target above the waterline, the other four undershooting slightly to hit below the waterline. The main danger in this sort of strike was the possibility of flying into your target. Being in a dive with a closing speed of 300mph, you had to pull out very smartly."
"Normally when making an attack on shipping, the dive at 45 degrees was started at 2,000 feet, opening up with machine guns as sighters at about 1,500 to 1,000 feet. Hopefully the cannons were to knock out the enemies guns, bridge and so forth, and we then fired the rocket projectiles at about 500 feet. These were set to form a pattern spread on impact, so that if aimed correctly about half hit the target above the waterline, the other four undershooting slightly to hit below the waterline. The main danger in this sort of strike was the possibility of flying into your target. Being in a dive with a closing speed of 300mph, you had to pull out very smartly."
Glider
Captain
Like the RN the Kriegsmarine used trawlers or vessels built using the design of a trawler for a number of duties and these were called Vorpostenboot. The weapons they were equipped with varied considerably and in the Coastal Forces book (Gordon Williamson) they illustrate one and its equipped with 3 x quad 20mm, 2 x single 20mm and what looks like an 88mm. They carried a serious amount of firepower and vastly more than an RN Trawler
OK, what altitude were they dropping from, was the Utah anchored or in motion, and did anyone notice that none of the level bombers could hit anything?
At 5,000 feet, it's a CEP difference of about 150 ft, or the difference between a 200 ft. diameter circle and a 500 ft. diameter circle. That means areas of 31,416 and 196,350 square feet, respectively. Remember, that's the area in which 50% of the bombs will fall: you've increased the area 6-fold.
The Wasp had an over length of 741 ft. and an overall beam of 81 ft. We'll call it a total area of 60,000 square feet. Its length exceeds the diameter of the 50% circle, but nominally we can estimate that 60% of the bombs dropped from a 90-degree dive will hit (5,000 ft.), while perhaps 18% of the bombs dropped in a 50-degree dive will hit.
That's an immense difference.
This ignores the differences in ability to track a maneuvering ship and of the difficulty that very-high angle dive bombers present to anti-aircraft gunner.
The Idaho was similarly equipped for the 1921 bombing tests (inaccurately known as the "Billy Mitchell" tests.
Wild_Bill_Kelso
Senior Master Sergeant
- 3,231
- Mar 18, 2022
That was an excellent video, not just the footage which was great, but also the planning and the context which was very well explained. Very chaotic strike scenes. You can see the rockets quite often missing but you can also see some hits especially when they released from very close range. The cannons hit a lot more often of course.
Feel sorry for those ship crews, that's some cold water to be suddenly plunged into, even if you still have all your arms and legs.
Wild_Bill_Kelso
Senior Master Sergeant
- 3,231
- Mar 18, 2022
I'd say that plus the proximity fuse
Were these tests done only with level bombers or dive-bombers?
I was told that General Mitchell wasn't just interested in level bombers (though he saw them as hugely valuable), but saw dive-bombers as having some use as he'd seen them in action in WWI with devastating effect.
AIUI level bombers only. It was twin engined Martin MB-2/NBS-1 aircraft that were used to sink the Ostfriesland.
Billy Mitchell and the Battleships | Air & Space Forces Magazine
A century ago, airpower pioneer Brigadier General Billy Mitchell led the bombing of the battleship Ostfriesland to prove aviation's importance to defense.
www.airandspaceforces.com
Mitchell's Brigade had various equipment across its squadrons
1st Provisional Air Brigade - Wikipedia
All this happened before the USN had a carrier. CV-1 Langley didn't complete her conversion from collier to carrier until March 1922, and it was 1923 before she began regular aircraft operations. It was the latter part of the 1920s before the USN began hanging bombs off its fighters to go dive bombing. It was from that line of development that the dive bomber came.
Good point. That said, some of the qualities that make an effective dive-bomber (high g-load) are useful for other things?
Shortround6
Major General
Not really.
Most dive bombers had too much drag (big fuselage and wing) and too few guns to play at being fighters, despite what is often written.
Most dive bombers had too much drag (big fuselage and wing) and too few guns to play at being fighters, despite what is often written.
Wild_Bill_Kelso
Senior Master Sergeant
- 3,231
- Mar 18, 2022
Well some of them had fairly heavy guns (SBD had a pair of .50 cals, the Ju 87D, SB2C both had a pair of 20mm cannons) but they were usually not fast enough to make good fighters, at least against other fighters. SBDs and Stukas shot down some other types of miscellaneous (seaplanes, torpedo bombers etc.) planes in a rather predatory manner, but against fighters, barring one or two famous flukes, they were typically in trouble.
That said, a dive bomber did typically survive both flak and fighter attack a bit better than say, torpedo bombers or most of the slower (below 300 mph) twin engine light bombers. The agility did help evade fighters, and the near vertical dive bombing attack, despite claims to the contrary, was both intimidating / demoralizing and fairly hard to draw a bead on.
The demoralizing effect on flak gunners was significant enough that Allied fighter bomber pilots used to put captured 'jericho trumpet' sirens taken from stukas onto their fighters in some cases, to enhance the intimidation factor.
That said, a dive bomber did typically survive both flak and fighter attack a bit better than say, torpedo bombers or most of the slower (below 300 mph) twin engine light bombers. The agility did help evade fighters, and the near vertical dive bombing attack, despite claims to the contrary, was both intimidating / demoralizing and fairly hard to draw a bead on.
The demoralizing effect on flak gunners was significant enough that Allied fighter bomber pilots used to put captured 'jericho trumpet' sirens taken from stukas onto their fighters in some cases, to enhance the intimidation factor.
Wild_Bill_Kelso
Senior Master Sergeant
- 3,231
- Mar 18, 2022
One other fact worth noting - several Allied fighter bomber and dive bomber (A-36) pilots that I've read have mentioned the 'rule' that one only made a single pass on a well defended target, especially a German target. This would maximize the effects of surprise, confusion and panic on the AA gunners, though it also meant the fighter bomber pilots themselves would have a shorter time to assess the target and were probably less accurate. Doing a second or third pass would increase the chances of getting hits or strafing effectively, but was considered "bad luck", as it usually meant someone was going to get shot down.
Both in pilot's accounts and in footage like that of the raids in the Fjords posted early in this thread, you can also see the effects of strafing on the targets prior to attack with the ordinance (whether bombs or rockets). In the Pacific the 5th Air Force specialized in coordinating strafing with low level ('mast head' and skip-) bombing and rocket attacks. Sometimes they would have Beaufighters attack from one side while the bombers attack from the other; or they would have A-20s or B-25s with multiple machine guns in the nose come in strafing sometimes from multiple directions before the bombs skipped in. All of this was important in making bombing attacks successful.
Both in pilot's accounts and in footage like that of the raids in the Fjords posted early in this thread, you can also see the effects of strafing on the targets prior to attack with the ordinance (whether bombs or rockets). In the Pacific the 5th Air Force specialized in coordinating strafing with low level ('mast head' and skip-) bombing and rocket attacks. Sometimes they would have Beaufighters attack from one side while the bombers attack from the other; or they would have A-20s or B-25s with multiple machine guns in the nose come in strafing sometimes from multiple directions before the bombs skipped in. All of this was important in making bombing attacks successful.
Shortround6
Major General
I am not real impressed with a pair of .50 cal guns (synchronized) for air superiority duties. The US Army gave up on that in the spring of 1940, (added .30s to the Tomahawk.) The US Navy had given up on it with the Buffalo and the the F4F-3.
The Ju 87D showed up in Spring/late winter of 1942, but that was the D-1. The 20mms don't show up until early 1943 with the D-7.
The SB2C with 20mm guns didn't show up until 1943.
You need more than speed, you need climb or the ability to actually turn without falling out of the sky. (climb is an indication of excess power available at low speed).
An Avro Anson claimed several 109s. The British were not dumb enough to send Anson's out on patrol against enemy aircraft.
Skua's shot down an Do 18 on the 20th of Sept 1939.
When you are desperate you do desperate things.
Planning on doing desperate things just to have another use for unsuitable aircraft is poor planning indeed.
buffnut453
Captain
Not to nit-pick but this claim was on 26 Sep 1939 and was the UK's first confirmed aerial victory during WW2. The Skua went on to make several more kills, including creating a few aces along the way.
That's not to say the Skua was effective as a fighter. It was too slow and under-armed. However, its performance under the circumstances is pretty decent, IMHO.
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